Giant cell arteritis: a review of classification, pathophysiology, geoepidemiology and treatment.

Giant cell arteritis is a chronic vasculitis affecting large and medium-sized arteries, most commonly the temporal and other cranial arteries. Temporal artery biopsy has long been the gold standard for establishing the diagnosis of giant cell arteritis. There is growing evidence that simultaneous color Doppler and duplex ultrasonography of temporal arteries of GCA patients represents a valid alternative for this somewhat invasive procedure. Ultrasonography and other imaging modalities such as magnetic resonance imaging and positron emission tomography have also provided evidence that involvement of the aorta and its proximal branches is much more common in giant cell arteritis than previously appreciated; it will be important to clarify whether these patients need to be treated more aggressively. It has long been known that patients with giant cell arteritis face a markedly increased risk of developing aortic aneurysms and of dying from aortic dissection. This raises important questions as to whether patients should be screened regularly for extra-cranial large-vessel involvement and whether and how treatment of patients with positive screening results should be adjusted. In this review we discuss the pathophysiology of this disease and also the issues of epidemiology and sex differences.